Former president Jimmy Carter has accused Newt Gingrich of using subtly racist
language to appeal to the extreme right in South Carolina.

In a rare interview, Mr Carter said that his fellow Georgian was employing a "subtlety of racism" that harked back to the time of segregation in the Deep South.

"I think he has that subtlety of racism that I know quite well, and that Gingrich knows quite well, that appeals to some people in Georgia – particularly the right wing," he told Piers Morgan in an interview on CNN.

The 87-year-old said he did not think Mr Gingrich himself was racist but that through his constant references to Barack Obama as a "food stamp president" and by continually linking of the black community to welfare payments he was making a coded appeal to bigots in the conservative state of South Carolina.

"He knows as well the words that you use – like welfare mommas and so forth – that have been appealing in the past, in those days when we cherished segregation of the races," Mr Carter said.

There was no immediate reaction to Mr Carter's comments from the Gingrich campaign, which is travelling South Carolina ahead of Saturday's primary.

Polls show Mr Gingrich gaining ground on Mitt Romney, the national frontrunner, as the Republican party's conservative wing seeks a way to prevent him from sealing a third straight victory.

Although Mr Romney is, on average, around 10 points ahead, his campaign was sufficiently concerned to by Mr Gingrich's rise to put out a new attack and dispatch a number of surrogates to attack his record as Speaker of the House of Representatives.